Assessment of exposure to nickel intake with selected cereal grains and cereal-based products

Overview

Mania et al. (2020) measured nickel in 56 cereal-grain and cereal-based product samples from the Polish retail market in 2019-2020. The study used graphite furnace atomic absorption spectrometry (GFAAS) after microwave acid digestion and compared estimated dietary exposure with the EFSA 2020 tolerable daily intake of 13 ug Ni/kg body weight per day. It is a primary Polish-market occurrence source for Ni in non-rice grains, pasta, flour, groats, flakes, and bran.

Key numbers

Concentrations are reported in mg/kg on an as-purchased product basis. The authors used middle-bound (MB) substitution for the main summary after 27% of analytical results fell below the food-matrix LOQ of 0.06 mg/kg.

Individual and subgroup values reported in the text:

• Cereal-grain Ni ranged from 0.10 mg/kg for rye to 4.80 mg/kg for millet.
• Roasted buckwheat had 1.81 mg/kg Ni.
• Oat flakes had 2.53 mg/kg Ni.
• Whole-grain pasta ranged from 0.20 to 1.79 mg/kg; regular pasta made from wheat flour ranged from 0.03 to 0.08 mg/kg.
• Whole-grain flour ranged from 0.23 to 2.12 mg/kg; wheat flour was below LOQ; spelt flour ranged from 0.14 to 0.18 mg/kg.
• EFSA 2020 occurrence data cited by the authors reported grains and grain-based products at mean LB-UB 0.31-0.33 mg/kg and P95 1.25 mg/kg.

Exposure estimates as percent of EFSA’s 13 ug Ni/kg bw/day TDI:

Methods

The study used 56 samples from the Polish market: 5 grain samples and 51 grain-product samples. Product groups were pasta (n=11), flours (n=13), groats (n=12), flakes (n=10), bran (n=5), and grains including wheat, rye, barley, and millet.

Nickel was measured with an accredited in-house GFAAS method using Zeeman background correction after microwave closed-vessel digestion. Approximately 0.5 g of sample was digested with 5 mL concentrated nitric acid and 1 mL hydrogen peroxide. The method was validated with NIST SRM 1515 Apple Leaves, which had a certified Ni mass fraction of 0.936 +/- 0.094 mg/kg.

Method performance reported by the authors:

The authors used EFSA’s substitution method for left-censored data: lower bound = 0, middle bound = half the LOQ, and upper bound = LOQ. Exposure estimates used Polish Central Statistical Office consumption data and WHO GEMS/Food Consumption Cluster Diets.

Speciation and methods caveats

• Nickel is reported as total Ni; no nickel species are distinguished.
• The study measured only Ni. Mentions of Pb, Cd, pesticides, herbicides, and other contaminants in the introduction are contextual and should not be routed as measured analytes from this source.
• The exposure estimates exclude bread, rice, and bakery products in the cereal-product scenario; do not generalize those percentages to total grain intake.

Implications

Standards work: The study is useful for nickel monitoring in non-rice cereal ingredients and grain-based products, especially where whole-grain, bran, oat, millet, or buckwheat components are present. It also documents that, at the time of publication, EU food law did not set general maximum levels for nickel in foodstuffs apart from food-additive specifications, while EFSA had identified grains and grain-based products as important dietary contributors.

Courses: The study is a clean teaching example of how processing fraction matters. Bran, flakes, and whole-grain products carried higher Ni than refined wheat flour and regular pasta.

App: Category means and P95 values can support Polish/EU context screens for Ni in cereal-grain products. They should be used as occurrence context, not as certification limits.

Wiki pages updated on ingest

• Nickel
• Wheat
• Oat
• Non Rice Grains
• Pasta
• Cereals
• Other grain products (oat, millet, quinoa, barley)
• Flour (wheat, corn, other)
• Pasta (wheat-based)
• EFSA — Nickel Tolerable Daily Intake (13 µg/kg b.w./day)

Verification notes

• Merge-enhanced 2026-05-18 from the full manual-fetch PDF path and SHA-256 recorded in frontmatter.
• Replaced stale/nonexistent wikilinks such as ingredients/oats, individual missing grain slugs, and regulations/efsa-nickel-tdi-2020 with current wiki slugs.
• Strict brand-firewall check: no consumer brands are named. Instrument and reference-material vendor names appear only in the Methods section and fall under the Part 12 instrument/reference-material exception.

Update history

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